位1的个数(算法)

题目: 位1的个数 编写一个函数, 输入是一个无符号整数, 返回其二进制表达式中数字位为1的个数 3: 011 -> 2 5: 101 -> 2 8: 1000 -> 1

1.x % 2 ? 1 -> count++; x = x >> 1; 2.x = x & (x - 1) 11000 = 24 x = 11000 x - 1 = 10111

=> 10000

while x != 0: count++ x = x & (x - 1)

python

def hamingWeight(self, n): rst = 0 mask = 1 for i in range(32): if n & mask: rst += 1 mask = mask << 1 return rst

java

int hammingWeight(uint32_t n) { int res = 0; for (; n; n &= n - 1) ++ res; return res; }